Prep the pan and oven: Heat the oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment, letting the sides overhang for easy lifting. Lightly grease the parchment and exposed pan.

Mash the bananas: In a large bowl, mash the ripe bananas until mostly smooth with a few small lumps. You should have about 1 1/4 to 1 1/2 cups mashed banana.

Whisk in wet ingredients: Add eggs, oil (or melted butter), yogurt, and vanilla. Whisk until well combined. Stir in lemon zest if using.

Mix dry ingredients: In a separate bowl, whisk flour (2 cups), baking soda, salt, cinnamon (if using), granulated sugar, and brown sugar until no lumps of sugar remain.

Combine gently: Add the dry mixture to the banana mixture. Stir with a spatula just until you no longer see dry flour. The batter should be thick and creamy. Do not overmix.

Toss the blueberries: In a small bowl, toss blueberries with 1 tablespoon flour to lightly coat. This helps prevent sinking. Fold them gently into the batter, saving a small handful for the top.

Fill and top: Scrape the batter into the pan. Scatter the reserved blueberries over the surface and sprinkle with turbinado sugar for a crisp, sparkly crust.

Bake: Bake for 55–70 minutes, until a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top browns too fast, tent loosely with foil for the last 15 minutes.

Cool before slicing: Let the loaf cool in the pan for 15 minutes. Lift it out using the parchment and transfer to a rack to cool completely before slicing. This helps set the crumb and keeps it from squishing.

Serve: Slice thick and serve as is, or warm slightly and add a swipe of butter, a spoon of yogurt, or a drizzle of honey.